Gaseous electric discharge device



June 24, 1941.

M. PIRANI ETAL GASEOUS ELECTRIC DISCHARGE-DEVICE Filed May 5, l932 lnvenfors: Mar'ceLLo Pirani,

Hans Ewest Ker-L Becker",

Their A'k'torneg.

Patented June 24, 1941 tJNlTED STATES "r rE c'ssaops aLEc'rarc prsonnnor. navrc Application May 5, 1932, Serial No. 609,547 f in Germany May 13, 1931 '10 Claims.

The present invention relates to gaseous electric discharge devices generally and more particularly the invention relates to such devices oi the positive column type having thermionic elec-= trodes and in which a condensibl'e vapor is used.

It is now known in the art that the intensity of the light emitted by such a device depends on the vapor pressure in the container of the deviceand that the vapor pressure depends upon the temperature. Slight fluctuations in the circuit potential causing slight temperature changes have an exaggerated effect on thevapor pressure and therewith the intensity of the light which is dependant on the vapor pressure. For example, in an electric discharge device having a mercury vapor filling if the temperature of the container varies over a range of 320 to 340 0., due to an increase in circuit potential, for instance, the vapor pressure will vary over a range of 375 mm. to 550 mm. If the circuit potential again drops to its normal value before the vapor pressure has receded to its normal pressure the device will drop out since the circuit potential is then not suflicient to maintain the discharge at the raised vapor Pressure.

An object of the present invention is to provide a method and a means for operating a high pressure, vapor, electric discharge device having thermionic electrodes wherein the effect of fluctuations in the line potential on the in-. tensity of the light emitted by the device is re-- duced to a minimum. Another object of the in vention is to provide a method for operating de- (Qi. lid-J22) vices of the above type wherein the operation of the gaseous discharge is assurred even with fluctuations of potential in the current supply to said device. A further object 01' the invention is to minimize the effect of temperature changes in the atmosphere surrounding the container of the electric discharge device on the intensity of the light emitted by said device. still Iurther objects and advantages attaching to the invention and to its use and operation will be apparent to those skilled in the art from the following particular description and from the appended claims. 7

The drawing shows one form 01. discharge device embodying our invention. The device illustrated comprises a container or envelopes I0 having electrodes l i--l I sealed in the ends thereof. The said envelope contains a gaseous at- T mosphere comprising a rare gas, such as argon,

and a quantity of .vaporizable material it, such as mercury.

The invention attains its objects by restricting the vapor pressure of the gaseous filling to a pressure at least 5% lower than thatpressure normal to the device at a given tube temperature. The simplest manner of accomplishing this is by limiting the quantity of thevaporizable material, such as mercury, introduced into the container of the device, to such extent that it is completely vaporized before the device attains its operating temperature. A greater quantity of the vaporizable material can be introduced into the container provided said material is maintained at a lower temperature than the operating temperature of the container of the device. This is accomplished by placing said material in an off-set chamber attached to the container and which is provided with a cooling means or which is protected from the heat generated in the container of the device, or both may be used when desired.

An electric discharge device operated in accordance with the foregoing method is not as sensitive, to fluctuations in the circuit potential as are like devices operating with a saturated vapor pressure. This is due to the fact that the unsaturated vapor pressure in an electric discharge device gives the device 9. volt ampere characteristic. By a negative characteristic is meant that an increase in the otential and in the current strength on the line causes the tube potential to decrease. Thus with our novel-device potential fluctuatlons in the line do not cause the usual excessive fluctuations in the intensity of the light emitted by the device and changes in the temperature of the container, caused by fluctuations of the atmosphere surrounding said container do not noticeably affect either the intensity of the light emitted by the lamp or the potential across the device. An electric discharge device operating with an unsaturated vapor pressure, 1. e., with the vapor in av superheated condition, in accordance with this invention, has. a very desirable efliciency range as can be seen by a comparison of the following two devices operating with a saturated operating temperature of 350 C. and a vapor invention, however, the quantity of the mercury introduced into the device is such, or the temperature of the mercury body in said container is controlled in such manner, as described here: tofore, that the vapor pressure in said container can never exceed 600 mm. so that even though the potential and the current on the line exceed that limit at which the corresponding temperature ,of the containergives a vapor pressure of 600 mm. the gaseous discharge will not "drop out" when the line potential and current drop back to normal due to the fact that the potential on the devices decreases as the line potential increases. The electric discharge device described above, if operated in accordance with the method described heretofore is capable of operation on 4 amperes instead of 3 amperes. The device does not then drop out and in addition the efficiency of the device is raised to approximately '70 lumens per watt. When the device draws 4 amperes a higher line potential than that given above must be used. Any suitable type of thermionic electrodes are used and when desired such electrodes consist of a metal shell coated with electronemitting material and having a heater in the interior thereof, commonly known as Hull electrodes, or are of the sintered, mixed metal and oxide type known as Pirani electrodes.

While we have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the method described and in its use and operation may be made by those skilled in the art without departnig from the broad spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. The method of operating an electric discharge device comprising an envelope having thermionic electrodes sealed therein, and a discharge supporting condensable vapor within said envelope, which consists in maintaining the vapor density in said device at a constant value irrespective of changes in ambient temperature or energy input to said device.

2. An electric vapor discharge device designed for operation with a given wattage of electrical input at a. given ambient temperature, said device comprising a. sealed envelope having thermionic electrodes sealed therein, and mercury vapor within said envelope, the heat radiating characteristics of said device being such that all of said mercury vapor is in a superheated condition when said device is operated under the designed conditions.

3. An electric vapor discharge device designed for operation with a given wattage of electrical input at a given ambient temperature, said device comprising a sealed envelope having electrodes sealed therein, at least one of which is an activated thermionic cathode, and vaporizable material within said envelope, the heat radiating characteristics of said device being such that all of said vaporizable material is in a superheated vaporized condition when said device is operated under the designed conditions.

4. An electric vapor discharge device designed for operation with a given wattage of electrical input at a given ambient temperature, said device comprising a sealed envelope having thermionic electrodes sealed therein, and a condensable vapor within said envelope, the heat radiating characteristics of said device being such that all or said vaporizable material is in a superheated condition when said device is operated under the designed conditions.

5. An electrical discharge device comprising an envelope having therewithin the thermionic electrodes, a filling of discharge conducting gas, and a vaporiza ble metal in sufficiently small quantity that it can be completely vaporized in the operation of the device, and means to supply sufllcient electrical energy to said device to completely vaporize said vaporizable metal: and during normal operation, to superheat the resulting vapor.

6. A high pressure electrical discharge device comprising an envelope having therewithin solid electrodes, a filling of discharge conducting gas, and a vaporizable metal in suiilciently small quantity that it can be completely vaporized in the operation of the device, and means to supply sufiicient electrical energy input to said device to completely vaporize said vaporizable metal, the heat radiating characteristics of the device and the said energy input being such that during normal operation there is present in said envelope a condition of substantial undersaturation of the atmosphere therein .by the metal vapor whereby said device is rendered substantially insensitive to variations in ambient temperature or energy input.

7. A high pressure electrical discharge device comprising an envelope having therewithin solid electrodes, a filling of discharge conducting gas, and a vaporlzable metal in sufficiently small quantity that it can be completely vaporized in the operation of the device, and means to supply suflicient electrical energy input to said device to completely vaporize said vaporizable metal, the heat radiating characteristics of the device and the said energy input being such that during normal operation there is present in said envelope 8. condition of substantial undersaturation of the atmosphere therein by the metal vapor to such degree that the pressure is at least 5 percent less than it would be if an excess of vaporizable metal were present and whereby said device is rendered substantially insensitive to variations in ambient temperature or energy in put.

8. An electrical discharge lamp comprising an envelope having therewithin thermionic electrodes, a filling of discharge conducting gas, and a va-porizable metal in sufllciently small quantity that it can be completely vaporized in the operation of the lamp, and means to supply suflicient electrical energy to said lamp to completely vaporize said vaporizable metal and, during normal operation, to superheat the resulting vapor.

9. A high pressure electrical discharge lamp comprising an envelope having therewithin solid electrodes, a filling of discharge conducting gas, and a vaporizable metal in sufliciently small quantity that it can be completely vaporized in the operation of the lamp, and means to supply sufllcient electrical energy input to said lamp to completely vaporize said vaporizable metal, the heat radiating characteristics or the lamp and the said energy input being such that during normal operation there is present in said envelope acondition of substantial undersaturation of the atmosphere therein by the metal vapor whereby said lamp is rendered substantially insensitive to variations in ambient temperature or energy input.

it). A high pressure electrical discharge lamp comprising an elongated envelope having theremeans to supply sumcient electrical energy input to said lamp to completely vaporize said mercury, the heat radiating characteristics of the lamp and the said energy input being such that during normal operation there is present in said envelope a condition of substantial undersaturation or the atmosphere therein by the mercury vapor whereby said lamp is rendered substantially insensitive to variations in ambient vtemwithin solid electrodes near its ends, a filling of u perature or energy input.

discharge conducting gas, and mercury in sufllclently small quantity that it can be completely vaporized in the operation of the lamp, and

MARCELLO. PIRANI. HANS EWEST.

KARL BECKER.

CERTIFICATE OF CORRECTION.

-'1 ate nt No. 2,213,176. June 21+, 191p.

mxcnnno Pmm, m AL.

It is hereby eertii'ieci that error .eppeu e in me printed epeciricntion of the above mmbered potent requiring correction ea follows: .Page 1}!iret co1u mn, .1ine 4 9, for the word."enve1=opee'! read --envelope-; end second column, line 26, before "volt" insert --negetive-- line 58; for "lamp" i-ead "device"; line k6, for,"de,vice" need --lemp--; page 2, secondcolumn, 1ine.15, cIaimj, Strike out "the"; and that the epic! Letters Patent should be read with this correction therein that the. one may conform to the record oi the case in the Patent Office.

Signe'd.and sealed this 26th day of Augu'st, A. D. 19141.

Henry Van Arsdale,

(Seal Acting Commissioner of Patents. 

